JP6074499B2 - Dual clutch transmission - Google Patents

Description

  The present invention relates to a gear arrangement in a dual clutch transmission, particularly a dual clutch transmission of a vehicle traveling on a road.

  In a dual clutch transmission in which the input shaft and the output shaft are coaxial, a small main guide bearing is disposed between the center shaft and the first input shaft. This guide bearing receives a large axial force at several gear speeds. These large axial forces arise from helical gears that receive gear occlusion forces when transmitting torque. These large axial forces are particularly problematic at gear speeds when there is no relative rotation in the main guide bearing. Large axial forces and no relative rotation are highly undesirable operating conditions for small bearings. Fretting wear can occur, leading to premature bearing damage.

  Patent Document 1 discloses an embodiment of the prior art in the introduction part of claim 1.

US Pat. No. 5,181,431

  One solution to this problem is to increase the size of the bearing. However, there is no space available for larger bearings.

  The object of the present invention is to bring a creative gear arrangement to the dual clutch transmission, which is intended to reduce the load on the guide bearing in the absence of relative rotation of the guide bearing.

  This object is achieved by a dual clutch transmission comprising first and second input shafts provided with first and second input means, respectively, a center shaft, a counter shaft, and first and second primary gear stages. Achieved. The first and second input means are normally first and second clutches. The first and second input shafts are arranged coaxially with the center shaft, and can transmit torque from the first and second input means to the counter shaft via the first and second primary gear stages. . This is a well-known arrangement and is used in some dual clutch transmissions.

  The first primary gear stage includes a first input gear and a first driven gear, and the first input gear is rotatably fixed to the first input shaft. According to the present invention, the first input gear is arranged on the center shaft, not on the previously known first input shaft.

  By arranging the first input gear on the center shaft instead of the first input shaft as previously known, the axial gear engagement force acting on the first primary gear is received and supported by the main shaft. So that the guide bearing is subjected to a smaller axial load.

  The first input shaft is preferably connected to the first input gear via a connection allowing axial play, which connection cannot transmit any axial load. This connection consists of a first part belonging to the input shaft and a second part belonging to the center shaft. One such suitable connection is a spline joint. The spline joint can be integrated, which includes engaging clutch teeth on the first input shaft and the first primary cut gear 332. The spline joint can instead include a bridging element that engages the clutch teeth on the first input shaft and the first primary cut gear. However, this connection is always engaged. The alternative joint can be an axially oriented dog clutch tooth.

  More preferably, the first input shaft is arranged with the first input gear on the tapered roller bearing, and the bearing can receive a relatively high axial load.

  On the other hand, disposing the first input gear on the cylindrical roller bearing is preferable from the viewpoint of cost with respect to the conical roller bearing.

  It is further advantageous that the first input can be axially displaced between a spaced axial position on the center shaft and the contacting axial position, but is always rotatably fixed to the first input shaft. The gear is arranged on the center shaft. In the spaced apart axial position, the first input gear is axially spaced from the first part of the connection and in the contacted axial position between the first input gear and the first part of the connection. Axial contact is possible. In the contacted position, an axial force acting on the input gear can be transmitted to the first input shaft, thereby further releasing the guide bearing from the axial load.

  What is predicted here is that the first input gear is displaced to the contacted axial position when transmitting the torque load in the first direction. This axial displacement is due to the gear occlusion force acting on the first input gear.

  The first input gear and the first driven gear are provided with helical gear teeth, so that when the first input gear transmits a torque load to the driven gear, the axial direction is in contact from the separated axial position. The axial displacement of the first input gear to the position starts.

  In order to achieve axial sliding of the first input gear, the first input gear is mounted on first and second roller bearings that can be slid thereon. The first input gear is provided with a radially inward projection between the first and second roller bearings so that axial displacement is possible. This radially inward projection is in a range shorter than the corresponding distance between the first and second roller bearings.

  In another embodiment of the present invention, a synchronization mechanism or dog clutch is provided on the first input gear that allows a rotatable connection between the first input gear and the center shaft. By closing the synchronization mechanism or the occlusal clutch, a direct connection between the first input shaft and the center shaft is achieved.

  The present invention will be described in detail with reference to the drawings.

1 illustrates a prior art dual clutch transmission. 1 shows a first embodiment of an inventive dual clutch transmission. 2 shows a second embodiment of the inventive dual clutch transmission. 2 shows a second embodiment of the inventive dual clutch transmission.

  FIG. 1 shows a prior art dual clutch transmission 200 when driven by an engine. The dual clutch transmission 200 is disposed inside the main housing 102, and has a first input shaft 221 and a second input shaft 222. The first input shaft 221 can be rotationally driven by the first clutch disk set 213, and the second input shaft 222 can be rotationally driven by the second clutch disk set 214.

  According to this prior art, the first primary gear teeth 232 are rotatably fixed to or integrated with the first input shaft 221, and the second primary gear teeth 230 are rotatably fixed to the second input shaft 222. Or they are integrated. The center shaft 224 is coaxial with the input shafts 221 and 222, and the counter shaft 223 is parallel thereto. The second input shaft 222 is supported on the clutch housing 201 by an input shaft bearing 225. A main guide bearing 229 is disposed between the center shaft 224 and the first input shaft 221. Sufficient support of the center shaft and the input shaft is achieved by two bearings between the input shafts 221 and 222.

  On the counter shaft 223, the second primary gear 131 meshes with the second primary gear teeth 230 of the second input shaft 222. The primary countershaft idle gear 233 meshes with the first primary gear teeth 232 of the first input shaft 221. Secondary countershaft idle gear 235 meshes with second secondary idle gear 134 on main shaft 224.

  FIG. 1 shows the transmission 200 in a state where the top sixth speed is active (broken line 6g) and the directly connected fifth speed is not active. The primary countershaft idle gear 233 is rotatably connected to the countershaft 223 by a first countershaft tooth clutch 248, a second countershaft idle gear 235, and a second countershaft tooth clutch 249. In addition, the direct tooth clutch 240 rotatably connects the first input shaft 221 and the center shaft 224. In FIG. 1, the second clutch disk set 214 is engaged. Accordingly, the second input shaft 222, the second primary gear teeth 230, the second primary gear 131, the counter shaft 223, the second counter shaft tooth clutch 249, the second counter shaft idle gear 235, the first counter shaft tooth clutch 248, The driving force can be transmitted to the center shaft 224 via the primary counter shaft idle gear 233, the first primary gear teeth 232, the first input shaft 221, and the direct tooth clutch 240.

  Arrows F1 and F2 indicate axial gear occlusion forces that act on the first primary gear teeth 232 and the second primary gear teeth 230, respectively, when the engine is driving the vehicle. The conclusion here is that the first input shaft 221 is pushed to the right. Thereby, the small main guide bearing 229 receives a large force. Since the direct tooth clutch 240 is engaged, the main guide bearing 229 has no relative rotation. The absence of large axial forces and relative rotation is a highly undesirable operating condition for small bearings. Fretting wear can occur, which leads to premature damage to the bearing.

  An embodiment of the present invention will now be shown and described in connection with FIGS. 2 and 3a, 3b, merely as an illustration of several modes of practicing the present invention.

  FIG. 2 shows a first embodiment of a dual clutch transmission 300 of the present invention driven by an engine. The dual clutch transmission 300 includes first and second input shafts 321 and 322, a center shaft 324, and a counter shaft 223.

  The inventive dual clutch transmission 300 corresponds to the prior art transmission 200 disclosed in FIG. Originally, however, the first input shaft 321 is not provided with any gear teeth. Instead, the first primary cut gear 332 is provided on the bearings 332b and 332c and supported by the main shaft 324. Further, the first primary cut gear 332 is rotatably connected to the first input shaft 321 by a first primary spline joint 321s, so that axial play is possible at the spline joint 321s. An axial gear occlusion force (arrow F 1) acting on the first primary cut gear 332 is supported by the main shaft 324 instead of the main guide bearing 229. The axial gear occlusion force (arrow F2) acting on the second primary cut gear 230 is received by the bearing 225.

  FIG. 2 shows the transmission 300 in an active state in which the sixth speed (6g) is active, whereby the dog clutch 240 is closed and the main guide bearing 229 has no relative rotation. When the engine is driving the vehicle, arrows F1 and F2 indicate axial gear engagement forces F1 and F2 acting on the first primary cut gear 332 and the second primary gear teeth 230, respectively. As can be seen from the figure, the main guide bearing 229 does not receive an axial gear occlusion force. Thereby, the risk of fretting wear damage is greatly reduced.

  The first primary cut gear 332 is rotatably connected to the main shaft 324 via the dog clutch 240, whereby the bearings 332b and 332c are not subjected to relative rotation. The bearings 332b, 332c are loaded by the gear biting force F1, but they are considerably larger than the main guide bearing 129, thereby avoiding problems with fretting wear. Therefore, by separating the first primary cut gear 332 from the first input shaft 321 and arranging it on the main shaft 324, it is possible to avoid the risk of fretting wear damage of the main guide bearing 229.

  The first primary spline joint 321 s provides a stable rotational connection between the first input shaft 321 and the first primary cut gear 332. The spline joint 321 s enables play in the axial direction between the first primary cut gear 332 and the first input shaft 321. Thereby, no axial force is transmitted from the main shaft 324 to the first input shaft 321 and vice versa.

  In conclusion, this dual clutch transmission 300 uses the rear primary gear stages 233 and 332 as the second gear stage for transmitting power from the counter shaft to the main shaft without exposing the main guide bearing 229 to fretting wear. Enable.

  The most common method of supporting gears that are subjected to load and relative rotation simultaneously is conical roller bearings that are arranged opposite each other. Axial forces can be transmitted in both directions between the gear and the shaft. Arrows F <b> 1 and F <b> 2 in FIG. 2 indicate axial gear occlusion forces that act on the second primary gear teeth 230 and the first primary cut gear 332 when the engine drives the vehicle. In the case of engine braking, which is the flow of driving force in the opposite direction, the direction of the axial force is reversed, thereby causing the main guide bearing 229 to receive a large axial force, while the relative rotation is still No. This raises the risk of fretting wear but is acceptable. This is because the engine brake torque is usually significantly less than the maximum drive torque and the frequency of engine brake is much less than the engine drive.

  However, direct transmission of the axial force from the first primary cut gear 332 to the first input shaft 321 is advantageous. Therefore, the main guide bearing 229 can be released from the axial gear occlusion force.

  FIGS. 3a and 3b show another embodiment of the inventive transmission, which reduces the risk of fretting wear during engine braking. The modified dual clutch transmission 400 includes an original first primary cut gear 432 supported on the center shaft 424 by cylindrical roller bearings 432b and 432c.

  Cylindrical roller bearings may allow some relative axial displacement. However, a carefully designed cylindrical bearing structure can control the transmission of axial forces. In the dual clutch transmission 400, this is done as follows: The first primary cut gear 432 has an inward projection 440 between the cylindrical roller bearings 432b, 432c. When the first primary cut gear 432 receives an axial gear occlusion force directed to the right, as indicated by arrow F3 in FIG. 3a, its inward projection 440 contacts the right cylindrical roller bearing 432c. The axial gear biting force is transmitted to the main shaft 424 and received by the bearing 128 between the center shaft 424 and the housing 102. This corresponds to the case where the engine drives the vehicle, as in FIGS. 1 and 2.

  In the case of engine braking, the arrow F4 in FIG. 3b indicates the direction of the axial gear occlusion force on the first primary cut gear 432. This gear occlusion force pushes the first primary cut gear 432 to the left. The inward projection 440 is designed not to contact the left cylindrical roller bearing 432b. Instead, the first primary cut gear 432 comes into contact with the first input shaft 321 in the axial direction, and the gear engagement force in the axial direction is directly transmitted thereto. As a result, the main guide bearing 229 is released from the axial gear engagement force even during engine braking.

  In the embodiment shown in FIGS. 2, 3 a and 3 b, the spline joint 321 s has engagement clutch teeth on the first input shaft 321 and the first primary cut gears 332 and 432. This is shown schematically in FIGS. 2, 3a and 3b.

  Alternatively, the spline joint 321s includes a bridging element (not shown) that engages with the clutch teeth on the first input shaft 321 and the first primary cut gear 332/432.

  Reference signs in the claims should not be construed as limiting the scope of what is protected by the claims, and their sole function is to make it easier to understand the claims. is there.

  As will be realized, the invention is capable of modifications in various obvious aspects, without departing from the spirit of the appended claims. Accordingly, the drawings and specification are to be regarded as illustrative in nature and not as restrictive.

131 Second primary gear 134 Second secondary idle gear 200 Transmission 201 Clutch housing 213 First input means (first clutch disc set)
214 Second input means (second clutch disk set)
221 First input shaft 222 Second input shaft 223 Counter shaft 224 Center shaft (main shaft)
229 Main guide bearing 230 Second primary gear teeth 232 First primary gear teeth 233 First input gear (primary countershaft idle gear)
235 Second countershaft idle gear 240 Direct tooth clutch (dog clutch)
248 First counter shaft tooth clutch 249 Second counter shaft tooth clutch 300, 400 Dual clutch transmission 321 First input shaft 321s Spline joint 322 Second input shaft 324, 424 Center shaft (main shaft)
332, 432 First input gear (first primary cut gear)
332b, 332c Conical roller bearing 432b, 432c Cylindrical roller bearing 440 Protrusion

Claims (9)

A dual clutch transmission (300, 400),
A first and second input shaft (321, 322) provided with first and second input means (213, 214), respectively;
● Center axis (324, 424),
● Counter axis (223),
● first and second primary gear stages (332-233, 432-233; 230-131),
The first and second input shafts (321, 322) are arranged coaxially with the center shaft (324, 424) and the first and second primary gear stages (332-233, 432-233; 230-). 131) torque from the first and second input means (213, 214) can be transmitted to the counter shaft (223) via
The first primary gear stage (332-233, 432-233) has a first input gear (332, 432) and a first driven gear (233),
The first input gear (332, 432) is rotatably fixed to the first input shaft (321), and the first input gear (332, 432) is not on the first input shaft (321). In the dual clutch transmission (300, 400) disposed on the center shaft (324, 424),
No gear teeth are provided on the first input shaft, and the first input shaft (321) is connected to the first input gear (332, 432) by a connecting portion (321s) that allows play in the axial direction. Dual clutch transmission (300, 400) connected to   The dual clutch transmission (300, 400) of claim 1, wherein the connection is a spline joint (321s).   The dual clutch transmission (300, 400) according to claim 1 or 2, wherein the first input gear (332, 432) is disposed on a conical roller bearing (332b, 332c).   The dual clutch transmission (400) according to claim 1 or 2, wherein the first input gear (432) is disposed on a cylindrical roller bearing (432b, 432c). The first input gear (432) can be displaced axially between the spaced apart axial position on the center shaft (424) and the contacted axial position on the center shaft (424). Placed in
At the separated axial position, the first input gear (432) is axially separated from the connecting portion (321s), and at the contacted axial position, the first input gear (432) is connected to the first input gear (432). The dual clutch transmission (400) according to claim 4, wherein axial contact with the part (321s) is possible.   The dual clutch transmission (400) according to claim 5, wherein the first input gear (432) is displaced to the contacted axial position when transmitting a torque load in a first direction.   The dual clutch transmission (400) according to claim 5 or 6, wherein helical gear teeth are provided on the first input gear (432) and the first driven gear (233). The first input gear (432) is mounted on and slidable on the first and second roller bearings (432b, 432c), and the first and second roller bearings (432b, A dual clutch transmission according to any one of claims 5 to 7, wherein a radially inward projection (440) disposed between 432c) is provided to allow displacement in the axial direction. (400).   The first input gear (432) is provided with a synchronization mechanism or a dog clutch (240) that enables a rotatable connection between the first input gear (432) and the center shaft (324). A dual clutch transmission (400) according to any one of claims 5 to 8.

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